``As a United Kingdom, we keep energy bills down for all consumers, regardless of where they live, and this works well, especially for people in Scotland.

``Without unrestricted access to the integrated GB market, the costs of supporting Scottish energy network investment, small-scale renewables and programmes to support remote consumers would fall on Scottish bill-payers alone.

This would add at least £38 to annual household energy bills and around £110,000 to energy costs for a medium-sized manufacturer in 2020.

``In addition, if the full costs of supporting large-scale Scottish renewables fell to Scottish bill-payers, the total potential increase would rise considerably up to £189 for households and £608,000 for a medium-sized manufacturer in 2020.

``Right across the energy mix, Scotland benefits from being part of the UK's strong, stable consumer and tax base, supporting thousands of jobs, creating new supply chains and cementing the energy sector as the engine room of the economy.''

The analysis paper concludes that the rest of the UK, with a range of power sources domestically and ``elsewhere'', would not need to purchase energy from Scotland.

The UK Government is also looking at grid connections to continental Europe.

But Scottish Energy Minister Fergus Ewing said Mr Davey's administration is likely to drive up bills. He underlined his commitment to keep the single GB market after independence and accused the British Government of mismanagement.

``Only a Westminster politician could fail to see the huge benefits of Scotland's abundant energy wealth to consumers across these islands,'' he said.

``Instead of accessing Scotland's reliable energy resources, he is talking of importing energy over interconnectors that don't yet exist from the European mainland where many countries face a similar energy supply concerns as the UK.

``You don't have to be an energy expert to see that that is somewhat problematic. Even more so when these interconnectors can then be used to export electricity as well as import electricity.

``Under EU rules, Mr Davey would not be able to prevent power flowing out of the UK to continental markets if prices were higher there, thus potentially worsening the UK's difficult position.''

Scottish consumers help subsidise renewable power in England already, he said.